2020年8月28日
[Postgres] Keep Data Integrity with Constraints
摘要： If the data in your tables do not have integrity, meaning there are missing rows, incorrect values, or duplicate rows, your table is not worth much. D 阅读全文
posted @ 2020-08-28 19:30 Zhentiw 阅读(152) 评论(0) 推荐(0)
[Postgres] Removing Data with SQL Delete, Truncate, and Drop
摘要： Delete: delete from Users where last_name = 'clark'; If you wanted to delete everything in our table, I mentioned you could just use the delete comman 阅读全文
posted @ 2020-08-28 19:22 Zhentiw 阅读(149) 评论(0) 推荐(0)
[Postgres] Using uuid-ossp extenstion
摘要： PostgreSQL allows you store and compare UUID values but it does not include functions for generating the UUID values in its core. Instead, it relies o 阅读全文
posted @ 2020-08-28 18:41 Zhentiw 阅读(148) 评论(0) 推荐(0)
[Machine Learning] Simplified Cost Function and Gradient Descent
摘要： We can compress our cost function's two conditional cases into one case: We can fully write out our entire cost function as follows: A vectorized impl 阅读全文
posted @ 2020-08-28 04:07 Zhentiw 阅读(146) 评论(0) 推荐(0)